which is non-positive. Hence the Higgs boson will never be on-shell and the Higgs propagator, \(1/(q^2-m_H^2+im_H\Gamma _H)\) , has then little dependence upon its width in the Standard Model (SM). We care about off-shell Higgs couplings because we would assume they are the same as the on-shell ones and measure the Higgs width using the so-called “off-shell” method [1]}, [2]}.
